test(client): add direction mapping tests for octant and entity facing (#540 review)

14 tests covering _octant_to_direction (all 8 octants + 2 fallbacks)
and _entity_direction (NPC default south, player facing 3 cases).
Closes review warning on zero test coverage for direction system.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/tests/test_sprite_integration.gd

@@ -193,3 +193,100 @@ func test_fog_update_runs_independently_of_entity_renderer_state() -> void:
 		).is_not_null()
 	GameState.visible_positions.clear()
 	GameState.visibility_sectors.clear()
+
+
+# -- Direction mapping: _octant_to_direction (S16-S12 through S16-S21) --------
+
+func test_octant_north_maps_to_north() -> void:
+	# S16-S12: "North" → "north"
+	assert_that(EntityRenderer._octant_to_direction("North")).is_equal("north")
+
+func test_octant_northwest_maps_to_north() -> void:
+	# S16-S13: "Northwest" → "north" (grouped with North per mapping spec)
+	assert_that(EntityRenderer._octant_to_direction("Northwest")).is_equal("north")
+
+func test_octant_northeast_maps_to_east() -> void:
+	# S16-S14: "Northeast" → "east"
+	assert_that(EntityRenderer._octant_to_direction("Northeast")).is_equal("east")
+
+func test_octant_east_maps_to_east() -> void:
+	# S16-S15: "East" → "east"
+	assert_that(EntityRenderer._octant_to_direction("East")).is_equal("east")
+
+func test_octant_southeast_maps_to_south() -> void:
+	# S16-S16: "Southeast" → "south"
+	assert_that(EntityRenderer._octant_to_direction("Southeast")).is_equal("south")
+
+func test_octant_south_maps_to_south() -> void:
+	# S16-S17: "South" → "south"
+	assert_that(EntityRenderer._octant_to_direction("South")).is_equal("south")
+
+func test_octant_southwest_maps_to_west() -> void:
+	# S16-S18: "Southwest" → "west"
+	assert_that(EntityRenderer._octant_to_direction("Southwest")).is_equal("west")
+
+func test_octant_west_maps_to_west() -> void:
+	# S16-S19: "West" → "west"
+	assert_that(EntityRenderer._octant_to_direction("West")).is_equal("west")
+
+func test_octant_unknown_string_falls_back_to_south() -> void:
+	# S16-S20: Unknown string → "south" fallback (safe default — viewer-facing per D-019)
+	assert_that(EntityRenderer._octant_to_direction("Unknown")).is_equal("south")
+	assert_that(EntityRenderer._octant_to_direction("invalid")).is_equal("south")
+
+func test_octant_empty_string_falls_back_to_south() -> void:
+	# S16-S21: Empty string → "south" fallback
+	assert_that(EntityRenderer._octant_to_direction("")).is_equal("south")
+
+
+# -- Direction mapping: _entity_direction (S16-S22 through S16-S25) ----------
+
+func test_entity_direction_npc_always_south() -> void:
+	# S16-S22: NPC entity → always "south" regardless of any data field.
+	# NPCs have no facing in v1 entity format; south is viewer-facing (D-019 angle).
+	var renderer := _make_entity_renderer()
+	GameState.player_entity_id = 1
+	# entity_id 99 is not the player
+	var dir := renderer._entity_direction(99, {"entity_id": 99,
+		"kind": {"variant": "Npc", "data": null}})
+	assert_that(dir).override_failure_message(
+		"NPC entity must always return 'south'"
+	).is_equal("south")
+	renderer.queue_free()
+
+func test_entity_direction_player_uses_player_facing() -> void:
+	# S16-S23: Player entity → uses GameState.player_facing via _octant_to_direction.
+	var renderer := _make_entity_renderer()
+	GameState.player_entity_id = 1
+	GameState.player_facing = "North"
+	var dir := renderer._entity_direction(1, {"entity_id": 1,
+		"kind": {"variant": "Player", "data": null}})
+	assert_that(dir).override_failure_message(
+		"Player entity with player_facing='North' must return 'north'"
+	).is_equal("north")
+	renderer.queue_free()
+
+func test_entity_direction_player_facing_east() -> void:
+	# S16-S24: Player facing "East" → "east"
+	var renderer := _make_entity_renderer()
+	GameState.player_entity_id = 1
+	GameState.player_facing = "East"
+	var dir := renderer._entity_direction(1, {"entity_id": 1,
+		"kind": {"variant": "Player", "data": null}})
+	assert_that(dir).override_failure_message(
+		"Player entity with player_facing='East' must return 'east'"
+	).is_equal("east")
+	renderer.queue_free()
+
+func test_entity_direction_player_facing_diagonal_uses_nearest_cardinal() -> void:
+	# S16-S25: Player facing "Northwest" → "north" (nearest cardinal mapping).
+	# Diagonal octants map to one of the four cardinal sprite sets.
+	var renderer := _make_entity_renderer()
+	GameState.player_entity_id = 1
+	GameState.player_facing = "Northwest"
+	var dir := renderer._entity_direction(1, {"entity_id": 1,
+		"kind": {"variant": "Player", "data": null}})
+	assert_that(dir).override_failure_message(
+		"Player entity with player_facing='Northwest' must return 'north'"
+	).is_equal("north")
+	renderer.queue_free()